class_docstr: Samples elements from [0, length) randomly without replacement.
  
  Parameters
  ----------
  length : int
      Length of the sequence.
code: def __len__(self):
      return self._length
  
imports: import numpy
label_desc: Use image node_id 3 for calling the RandomSampler obj's underlying member method code with example usage: obj.__len__() and returns: self